Insulating tubing for electrical conduits and method of making same



O. REY.

INSULATING TUBING FOR ELECTRICAL CONDUITS AND METHOD OF MAKING SAME.

APPHCATION FILED MAY I, 1919.

Patented Dec. 12, 1922.

Patented Dec. 12, 11922.

estates.

OSCAR REY, 0F ZURICH, SWITZERLAND.

INSULATING TUBING FOR ELECTRICAL CQNDUITS AND METHOD OF MAKING- SAME.

Application filed May 1, 1919. Serial No. 293,903.

To all whom it may concern.

Be it known that T, OSCAR REY, a citizen of the Swiss Confederation, and residing at Zurich, Switzerland, have invented certain new and useful Improvements in Insulating Tubing for Electrical Conduits and Methods of Making Same, of which the following is a specification.

' This invention relates to improvements in and methods of making insulating tubing.

An object of the invention is to make insulatin tubing having a uniform insulating reslstance at all points of the tube.

Another object of the invention is to improve the method of making a tube having the final result above stated by inserting a tube having a uniform layer of insulating material into a metallic casing or covering, and subsequently heating the parts to cause the insulating medium to adhere to the me tallic tube and form a unitary insulating tube.

Other objects and the details of construction and operation are clearly pointed out in the following description and claims.

In thedrawing, the figure shows a cross section of tube constructed in accordance with the invention.

a indicates a tube, preferably of paper or other suitable materiah adapted to form the inner portion of the finished insulating tube. This tube is first covered with a coating of insulating material, which is a uniform thickness at all points and which is allowed to become dry and hard after being applied to the paper tube and in the final product is indicated at b. The tube 0 which forms the outer portion of the finished article is made of metal and in practice drawn aluminum has been found to be better suited to use in following out the method of, this invention. In their relation to each other, the inner diameter of tube '0 and the outer diameter of tube or. with the insulating covering thereon, is such that tube a with the insulation I) will have a sliding fit in tube 0.

Tube awith its insulating cover 6 is forced into tube 0 by any suitable means,

and to aid in forcing one tube into the other,

the outside of the insulation Z: is greased,

which materially reduces the friction between the engaging surfaces of the tubes.

After the operation above is complete, the tubes are heated sufliciently to soften the insulating medium to such a point as will cause it to adhere to the tube a, which will make substantially a unitary tube structure.

In constructing the insulating tube in this way, it is possible to make the insulating coating of uniform thickness thruout, which will have the maximum insulating quality for the amount of material used.

The tube a with its insulating coating 6 substantially fills the tube 0 and just allows enough room to permit one to be forced into the other as above pointed out.

It is to be noted that the insulating medium b is in a cool, dry and hard state when it is forced into tube 0, and due to this, the surface will not be damaged which would impair its insulating qualities.

Claims:

1. A method of making an insulating tube, consisting in coating one tube with a uniform layer of insulating material and in serting said coated tube into a tube sufficiently large to make a sliding fit and subsequently heatin the tubes to cause the 1nsulating materia to adhere to the outer tube.

2. A method of making an insulating tube, consisting in coating one tube with a layer of insulating material, the peripheral surface of the layer being concentric with the tube and inserting the coated tube, the insulating coating being in a hard state into a second tube, the inside diameter of which is slightly larger than the diameter of the surface of the insulating material to form a sliding fit, and subsequently heating the tubes to cause the insulating medium to adhere to the outer tube.

3. The method of making insulating tubing, which consists in uniformly coatlng a tube with suitable insulating medium, greasing it, next forcing it into another tube, and then heating the combination to the softening point of the insulating intermediary.

OSCAR REY. 

